I heard that the creaters of Left 4 Dead 2 and Resident Evil 6 are crossing over games. Left 4 Dead has made a DLC for Resident Evil which allows the gamer to play either Coach, Ellies, Rochelle or Nick within the Resident Evil world. While Resident Evil (Valve) are making a DLC for Left 4 Dead where two characters from Resident Evil will be placed within the world of Left 4 Dead. This means that any zombie fan would probly be crapping themselfs by now. As for me, I believe this could "possible" work really effeciently with each other.